Will Hillary Clinton support a $15 minimum wage?

A $10 minimum wage? That's so 2014.

If Hillary Clinton wants to woo the left, she'll likely have to support $12 to $15 an hour.

President Obama made waves in his 2013 State of the Union address when he unexpectedly announced he wanted to raise the federal minimum wage to $9 an hour, from the current $7.25. A year later, he called for $10.10 an hour.

But advocates and lawmakers on the local level have moved well beyond that $10 rate. Seattle and San Francisco have raised their minimum wage to $15, while Massachusetts' rate is now $11. Lawmakers in other states, including Oregon and California, also want to boost the floor on wages.

Senator Patricia Murray of Washington and some of her Democratic colleagues want to see the minimum wage raised to $12 by 2020.

"The days of $9 to $10 an hour are over, for sure," said Tsedeye Gebreselassie, senior staff attorney at the National Employment Law Project, one of the groups involved in the 'Fight for $15' movement to raise the wages of fast-food workers and others.

Tens of thousands of low-wage workers marched on Wednesday to demand higher wages. Clinton voiced her support for the movement via Twitter, but didn't put a number on it.

Hillary Clinton sent this tweet to marchers on Wednesday.

The project believes presidential candidates that are serious about rebuilding the middle class need to support raising the minimum wage to at least $12 an hour and to commit to additional hikes in the future. It recently published a report showing that 42% of American workers make less than $15 an hour.

"Low-wage occupations in sectors such as retail, home care and restaurants are among the fastest-growing in the country," said Christine Owens, the group's executive director. "If we want an economy that is balanced and shares prosperity fairly, we must raise wages in these sectors so that they can serve as the cornerstones to rebuilding our nation's disappearing middle class."

Public pressure to raise wages has already pushed several companies to hike pay. Walmart will boost its minimum wage to $10 by next Feb. 1, while starting pay at 1,500 McDonald's-owned restaurants will increase toat least $1 an hour more than the minimum wage set by local laws, as of July 1.

Clinton has long supported raising the minimum wage. As a senator, she introduced legislation in 2007 to increase the rate to $9.50, and as first lady, she advocated for the successful 1996 push to boost it to $5.15, according to Correct the Record, a pro-Clinton web site.

More recently, Clinton has voiced support for raising the rate, but hasn't put a number on it. Her spokesman did not return emails seeking comment.

A recent report by the Center for American Progress, run by a former top Clinton policy adviser, may give some insight into her thinking. The report on building prosperity recommended setting the wage to at least $10.10 an hour, which would prevent full-time workers from living in poverty.

But supporting a minimum wage increase can mean walking a tightrope between workers and businesses, which Clinton also needs to court. Many business owners have said they can't afford a rate hike and any boost will cost jobs.

A 2014 Congressional Budget Office report shows the conflict between the two sides. Raising the minimum wage to $10.10 is projected to lift 900,000 workersout of poverty, but it would also mean the loss of 500,000 jobs.